Brake mechanism



'.l. G. oE'rzEL.

BRAKE MECHANISM Feb. 6, 1945.

3 Sheets-Sheetl Original Filed April 4, 1941 J. G. OETZEL Feb. 6, 19415.

BRAKE MECHANI SM 5 Sheets-Sheet 2 Original Filed April 4, 1941 N V55/733V 4 Cn Ceo/"gif 066e/ liv l'/ rToQdej/s Feb.. 6, V1945. J. G, oETzEL Re. Z22,598

BRAKE MECHANI SM original Filed April 4, 1941 5 sheets-*sheet :s

Reissue.: Feb. s, 1945 y Re. 22,598

BRAKE MECHANISM John George Oetzel, Beloit, Wis., assignor to Warner Electric Brake Manufacturing Company, South Beloit, Ill., a corporation of Illinois Original No. 2,352,218, dated June 27, 1944, Serial No. 386,775, April 4, 1941. Application for re issue November 24,1944, Serial No. 564,949

(Cl. 18s-78) 13 Claims.

' This invention elates generally to friction brake mechanisms of the character used on automotive vehicles and, Ain certain of its aspects, has more particular reference to brakes of the so-called wrapping or self-energizing type. i

One object is to provide a brake mechanism of the above general character in which the actuating and reactionary forces are applied to the actuated friction element in a novel manner so as to be balanced with respect to the longitudinal center line. v

A more detailed object is toy provide anchoring and actuating surfaces on the ends of the friction elements spaced both radially and Acircumferentially but both disposed in-the plane of the center line of the element.

' Still another object is to provide a novel anchor construction.

A further object is to provide tuating mechanism.

Other objects and advantages of the invcnA tion will become apparent from the following detailed description taken in connection with the `accompanying drawings, in which.

Figure 1 is an axial sectional view of a brake embodying the novel features of the present invention, the section being taken along the line I I of Fig. 2.

Fig. 2 is asection taken along the line 2 2 of Fig. 1.

Fig. 3 is a fragmentary view similar to Fig. 1 showing the elements in actuated positions.

Figs. 4 and 5 are sections taken along the lines 4 4 and 5 5 of Fig. 1.

Fig. 6 is a fragmentary perspectiveV view of the brake anchor member. y

Fig. 7 is a section taken along the line 1 1 of Fig. 2.

Fig. 8 is adiagram showing the parts of the transmitting connection and the forces acting The brake mechanism'shown for purposes of.

illustration is of the internal expanding type adapted for use with a drum Il with aninturned a novel aciiange II bolted to the vehicle wheel or other part to be braked and having an internal cylindrical surface I2- adapted to be gripped by a non-rotatable friction element of the brake mechanism. The latter is supported by an anchor member indicated generally at I3 and secured by a means such as bolts Il to a plate I5 which closes the open end of the drum and is carried by an axle housing orother non-rotatable part. I

In the present instance, the lannular friction element comprises two semi-circular shoes IG either flexible or rigid and arranged in end to end relation. As shown, each shoe comprises a curved band Il having a segment I8 of suitable friction material riveted or otherwise secured to its outer surface. Elongated lugs I9 welded along the center line of the shoe bands I1 are received in guide notches 20 on brackets 2I which are rigid with lugs 22 on the anchor member I3. Thus, .the shoe is held against lateral movement but is guided longitudinally during'expansion of the shoes within the drum.

In the form shown, the anchor member I3 comprises a ring-like steel casting with a centrai aperture 23 adapted to ilt over the axle and with holes 2l through which the bolts I4 may be entered. The lugs 22 project radially from oppositesides .of the ring. Along a diameter 24 at right angles to the 'lugs 22 are two arms 25 converging outwardly to points adjacent the internal drum surface and lying adjacent the plate I5 so as to be onset laterally from 'the longitudinal center line SII of thevshoe i8. Integral with and projecting laterally from the ends of the arm 25 are spaced lugs 26 rigidly'connected at'their free ends by a separate bar 2i welded to the lugs.

The oppositely facing flat outer sides 29 of the lugs are disposed parallel to the diameter 24 and constitute anchor abutments engageable with the dat surfaces 32 on hardened blocks 33 on the ends of the brake shoes.V The latter blocks are welded to the ends of the shoe bands I1 and the ends of tapering bracket plates ll which are welded along the inner surfaces of theA bands and disposed on opposite sides of the center line 32. The brackets nearest the anchor member I3 lie against flanges 35 which thus serve as guides for the shoe ends in the movementI of the latter toward and away from their anchors. As a result, the reactionary force applied to the anchoredend of the shoe is always balanced with respect to the shoe center line.

Either of the adjacent shoe ends may be vmitample -A ingthebrakes.

moved circumferentially away from its anchor to apply the brake. the line of action ofthe actuating force also being balanced' with respect to the shoe, center line. Herein this actuating means comprises a crank 36 having a hub 3] pivoted adjacent the peripheralsurface of the friction element on a pin 38 which is disposed in the recess 39 between the anchor lugs and projects through the anchor arm 25 and the plate 21' by whichy the hub is held against end- Wise movement. The free end of the crank is disposed to one side of, the brakeshoes. On the other side of the shoe and integral with the hub 3l is an arm 40 which receives witha press fit one end of a lhardened pin 4I projecting parallel armature ring 62 supported from the drum flange I I through the medium of tangentially extending spring arms 6 3 which constantly urge the armature into light mechanical contact with the' magnet face.

Rigidly secured tothe back'of the magnet as by welding are two pairs of lugs 34 disposed in recesses B5 between the flange 52 and the arms 25 of the anchor-member I3 and projecting inwardly toward the drum axis. Between the lugs of each pair is a hardened pin 5B rigid with and projecting -laterally from the free end of the to thecrank axis with its other end supported y by the -crank proper. The pin thus provides arcuate surfaces adapted for rolling contact withthe surfaces 42 of hardened blocks 43 onv the ends of eiitensions 44 of the shoe brackets 34,l these surfaces 42 extendingparallel to the drum diameter 24. Preferably, the edges of the cranks 36 and the arms 40 are beveled as in- X dicated at 4|)s (Fig. '1)v and coactwith the shoe. ends 43 to' perform the additional function of guiding these ends into accurately defined lateral positions as the shoes are contracted.,` The possibility of incomplete. return of the parts to fully released position dueV to misalinement of the parts is thus avoided and theanchored shoe end is always maintained properly centered re1-4 -ative to the shoe center line.

The extensions project beyond the anchor A surfaces 23 and lie inside of the stops 26. By .thus spacing the anchor and'actuating surfaces 23 and 42 of the shoes both-radially and circumferentially of the drum, the areas of contact with the surfaces 29 and the pin 4l are balanced with respect to the center line of the shoes and there is no twisting tendency during application of the brake.'V Coiled contractile springs 45 stretched between pins 46 connecting the shoe brackets 34 and lugs 41 on the anchor member I3 urge the shoe-ends toward the brake-released position in 'which the crank 3l is disposed radially and the surfaces 23 and V42 on each shoe` end are in abutment with thelugs 23 and the pin 4l as shown in Fig. 1.

' To reinforce .the anchor member I3, ribs 43 are formed integral with the latter along edges ofthearms. Thesearelocatedsoas topermovement of the cranks 36 in actuatwnnethecrunks :s maybe actuated invarious ways; a power operator of the momentum type is employed in the present instance. As shown,

the operator includes an annular magnetic 'ring 5l concentric with the drum axis and mounted to oscillare on a bushing 5| supported by a ilange 52 on theY anchor member I3. The magnet lies in the plane of the'biake shoes and is held loosely against a backing surface 53 (Fig. 5)l on the ancrank 38 which lies behind the magnet. It will be observed that the engaging surfaces 68 of the lugs 64 converge inwardly toward each other and the diameter 24, so that as the pin moves out along its actuating lug in applying the brake, the actuating force will continue to be applied perpendicular to the crank arm. 4

One purpose of this is to compensate for the decrease in the effective 'moment arm of the vactuating force which would occur as the `crank 36 moves away from released position if the surfaces 63 were disposed parallel to the diameter 24l in the brake-released position. The direction of the force applied'by the surface' 68 to the pinv '66 being normal to the surface, it will be observed progressively until the pin 5B reaches the position shown in dot-dash outlinev after which the length of the arm decreases progressively. In' the position shown in full lines, the moment arm has decreased to a value Rn. By th'us varying the eiec tive moment arm of the actuating force, the loss of leverage incident to the crank movement is reduced to a negligible value.

Energization of the magnet winding 6l produces a proportional gripping engagement between the rotating armature and the friction face of the magnet ring causing the magnet te 'turn with the armature. This movement is communicated through one lug 64 'of each pair to the pins 63 which ride outwardly along the lugs as the free ends of the crank arms 36 move with the magnet. -The lugs, since they project from the' lever pivot in the same direction as the crank arms, move in the direction of drum rotation and'- shift one end of each shoe away from its anchor depending on the direction of drum rotation (see Fig. 3). This results in expansion of theshoes and initiation of the self-energizing action to create a powerful braking eiiect in the manner described above. After the clearance between the g shoes and the drum has been taken up. slippage' occurs between the magnetand armature .faces y until the wheel stops revolving, the` brake being Vchor member by a spring clip 54 supported by pins y on the magnet urge the latter circumferentially Vj" toward brakereleased position while permitting of movement in either direction away from this position. The magnet is energized byya winding 60 disposed between inner and outer poles which terminate faces substantially flush with the surheld set so long as the magnet remains energized. When the magnet winding is denergized, th'e springs 45 and 53 coact to return the 'shoes and the magnet to released positio With the brake shoes mounted and actuated in the manner above described, it will be'observed that only oneend of each shoe will be actuated *between the brackets 2l and elongated eyes 53- face of segments 5| of friction-material supported between the poles. The magnet coacts with a :dat

while other end anchors. As a result, each' shoe 'constitutes the seat of a selfenergizing action which builds up through drum circumference and 'therefore -is maintained within controllable limital Both the actuating and reactionary forces incident the brake are, by virtue of the radial and circumferential spacing of the anchoring andactuating 4surfaces 2l and 32. directed lin the plane of the onlvI half of the tls-application of i shoe center so that lthe position of the shoes relative to the drum is maintained accurately.

I claim as my invention:

l. -A brake mechanism having, in combination, an annular expansible friction element having lin ner and outer surfaces on its ends spaced apart 4both radially andv circumferentially with the inner surfaces on the diiferent ends disposed generally radially and closer together than the outer surfaces, anchoring means abutting against said outer surfaces, a crank swingable about a xed 'pivot disposed between said outer surfaces outwardly beyond said inner surfaces and adjacent the peripheral surface of the element, and surfaces on opposite sides of said crank intermediate the ends thereoffacing circumferentially in opposite directions and engageable with either of the inner end surfaces one at a time to move such end circumferentially away from its abutment.v

2. A brake mechanism having, in combination, an annular expansible friction element having its ends spaced apart and each end having two end surfaces spaced apart both radially and circumferentiallyand disposed substantially radially and 11p-the plane of the center line of said element, anchoring means engageable with one surface on each of said ends, a fixed pivot extending parallel to the axis of said element, an arm swingable on said pivot and projecting inwardly between said ends, and circumferentially facing side surfaces on opposite sides of said arm engageable selectively with one or the other of said other element surfaces to move the latter circumferentially away from said anchoring means v when said arm is swung away 'from brake-released .'position, said pivot being disposed adjacent the periphery of said element outwardly beyond the points of engagement between said ends and said surfaces.

3'. `A brake mechanism having, in combination, an annular expansible friction element having its ends spaced apart, each of said ends having two end surfaces spaced apart both radially and circumferentially' and disposed substantially radially and in the plane of the Acenter line of said element, anchoring abutments engageable with one surface onthe respective ends, a crank pivoted adjacent the peripheral surface of the element to turn on a fixed axis and projectingl inwardly, said crank having side surfaces facing circumferentially in opposite directions and disposed equidistant from the axis of the element and adjacent the other of said end surfaces, and means for swinging said crank in one direction or the other away from centered position to cause bearing engagement between one of said side surside walls, actuating means engageable with the free inner ends of said crank arm. and extensions of said shoe ends projecting toward each other and past said stop abutments with their ends abutting said crank arm inwardly from its pivot, the areas of engagement between said abutments, said abutment surfaces, said extensions and said crank arm being disposed on the longitudinal' center line of said friction means whereby the actuating and reactionary forces are balanced with respect to such line.

5.. A brake mechanism having, in combination, an annular friction element having ends spaced apart, an anchor member projecting outwardly and being offset laterally from thecenterline Y of said element, circumferentially spaced lugs projecting laterally from said member and providing stops abutting against said ends and alined with the center of said element,` a bar rigidly connecting the projecting ends of said lugs, and

means for expanding said element comprising a device engageable with an end ofsaid element in the plane of the center line thereof and swinglaterally from the center line of said element,V circumferentially spaced lugs projecting laterable on a pivot supported by said member and saidbar and disposed between said 1ugs.-

6.. A brake mechanism having, in combination, an annular friction element having ends spaced apart on one side of its periphery, an anchor member projecting outwardly to a point adjacent said periphery, circumferentially spaced lugs projecting laterally from said member andproviding labutments engageable with said ends, a bar connecting the free ends of said lugs, a pivot disposed between said lugs and supported at opposite ends by said-'member and said bar, and. expanding means for said element mounted on '1. A brake mechanism .havingyin combination, an annular friction element having ends spaced apart on one side of its periphery, lan anchor member having an arm projecting outwardly to a point adjacent said periphery and being offset ally from said arm and providing stops abutting against said ends, a crank pivotally supported by said arm between said lugs and swingable parallel to the arm, means on said crank engagefaces and the corresponding end surfaces of said element and circumferential movement oi.' the engaged element surface away from its abutment, said fixed pivotal axis being disposed outwardly beyond the points of engagement between said end and side surfaces. l

4. A brake mechanism having, in combination, a non-rotatable anchor member centered with.-

respect to an axis and providinga hollow stop having side ,walls spaced -apart along -said axis and end walls spaced circumferentially,the outer surfaces of said end walls providing oppositely facing abutments, annular expansible `friction means having end portions disposed on opposite sides of said vmember with abutment surfaces normally contracted against said stop abutments,

an inwardly projecting crank arm having a fixed pivot. extending between and supported by said 'able with an end of said element to apply an expanding force thereto, 'and reinforcing ribs extending along the edges of said arm beyond the normal range of oscillation of said crank.

8. A brake mechanism having, in combination,

an annular friction `element having ends spaced apart on one side of its periphery, an anchor abutting one of said ends in the plane of the center line of the element, a crank swingable about an axis between said ends and parallel to the axis of the element and havingtwo arms disposed on opposite-sides of said plane, means extending between said arms and providing an arcuate surface having bearing engagement in said plane with the other of said ends, and means for actuating said crank to expand said element.

"19.A brake mechanism having, i'n combination, an arcuate friction element having ends spaced apart, an anchor abutting one of said ends in *thel plane ofthe center line oi' the element, a crank swingablef about an' axis between said ends and parallel to the axis of saidlement and having two armsdisposed on opposite sides of said plane,

means extending between said arms and providing an larcuate'surface having bearing engagement .in said plane with the other of said ends, means for'actuating said crank, and edge surfaces I on said arms coacting with the edges of said actuated end to guide the latter in between the arms in returning to brake-released position.

10. A brake mechanism having, in combination, an arcuate expansible friction element with its ends disposed adjacent each other, each of said ends having two circumferentially facing abutments thereon, a, member disposed between and engageable with the two outer abutments on the respective element ends to anchor one of said ends or the other, the engaging surfaces of said member and abutments being shaped to permit freedom of outward radial movement of the end while anchored against said member, an inwardly projecting arm swingable in opposite directions about a xedaxis disposed between said ends and extending parallel to the axis of said element, means rigid with said arm and disposed between said other two abutments for circumferential engagement with one or the other thereof depending on the direction of movement of the arm away from normal brake-released position. the other element end remaining ,fixed -against said member,'and actuating means for moving the inner end of said arm selectively in either direction, said arm axis being disposed outwardly beyond the points of engagement between the arm and the abutments engaged thereby.

1l. A brake mechanism having, in combination, an anchor, an annular expansible friction element having its end'surged into abutment with said anchor and shapedfor freedom of radial movement relative to the anchor while engaging the latter, pivot means extending parallel to the axis of said element between said ends and adjacent the Aperiphery of the element, crank means swingable on said pivot means and projecting radially and inwardly therefrom, said crank means having side surfaces intermediate its ends facing circumferentially in opposite directions and spaced inwardly from said pivot means equidistant from the axis of said element, substantially parallel radially disposed surfaces on said element ends disposed -adjacent and engageable with said side surfaces, said pivot means being fixed relative to said `anchor and disposed outwarcily beyond the points of engagement between said side surfaces and said abutment, and means connected to the inner end of said crank means and operable to swing the crank means-in one direction or the other away from said element surfaces circumferentially away from said anchor while the other element end remains against said anchor.

12. A brake mechanism adapted for use'with a rotatable drum having an internal cylindrical surface, said mechanism comprising a fixed pivot extending parallel to the axis of said drum and disposed closely adjacent said surface, an anchor member disposed adjacent said surface and having abutments spaced circumferentially from the surfaceof said pivot on opposite sides thereof and facing circumferentially in opposite directions, an expansible friction element extending around said surface and having its ends urged against the respective abutments and free to move outwardly therealong, a crank arm swingably supported on and projecting radially and inwardly from said pivot, said crank having side surfaces facing circumferentially in opposite directions and spaced inwardly from said pivot and equidistant from the drum axis, substantially parallel radially disposed surfaces on said element ends disposed adjacent and engageable with s'aid side surfaces, said pivot being disposed outwardly beyond the points of engagement between said crank and said element, and actuating means engageable Vwith said crankinwardly from said crank surfaces and operable to swing the crank in one direction or the other away from brake-released position depending on the direction of drum rotation whereby to move one of said element surfaces circumferentially away from said anchor while the other element endl remains against said anchor.- l

13. A brake mechanism having, in combination, an annular expansible friction element having ends disposed adjacent each other and spaced circumferentially, a hollow non-rotatable member disposed between said ends and providing abutments for anchoring one or the other of the ends, a pivot disposed within said hollow anchor Ymember and iixedly supported thereby, a crank arm swingable on said pivot with its free end projecting radially and inwardly from said mem-v ber, and surfaces on the sides of said crank arm engageable with said ends to move one orthe other end away from said member.

JOHN GEORGE OETZEL. 

